Dr. Hayes Columns — The Life Expectancy Gap, Part 3: The Test

Part 1 was about the table. Part 2 was about the body. Both come before illness. Part 3 asks a different question: once a disease has taken hold, who finds it earlier? The clearest place to see the answer is the cancer survival rate by country, where the same disease ends very differently depending on the system around it.

The same disease can end very differently depending on when it is caught. And when it is caught depends partly on a person’s luck, but heavily on what kind of screening system a country has built.

This part looks at the question from two angles. One is why survival for the same cancer differs so much from country to country, using stomach cancer. The other is how much survival changes within a single country depending on when the cancer is found, using breast and colorectal cancer by stage. The second angle shows the value of screening most clearly.

In my own work, I see the cases where someone arrives a little too late. Screening is the effort to turn that “a little earlier” into a system, rather than leaving it to a person’s vigilance.

As in Parts 1 and 2, the point of this data is to see the situation accurately and improve from there. It is meant to show how the same disease can take different paths depending on when it is found, and depending on the country a person lives in.

Cancer Survival Rate by Country: The Same Stomach Cancer

The U.S. figure of 39.8% is the most recent SEER number for all stages combined. In Korea, the five-year relative survival for stomach cancer has climbed from about 55% in the program’s early years to roughly 77% in the most recent data from the Korea Central Cancer Registry. Japan reports a figure above 70% in its national clinical registry. The cancer survival rate by country tells the same story across these three: it is the same disease, and survival in Korea and Japan is close to double the American figure.

One point belongs here in fairness. The incidence of stomach cancer in the United States is far lower than in Korea or Japan. Because the disease is less common, screening every American adult with an endoscope would not be a sound use of resources, so the United States does not do it. This is not a story about one country being careless. It is a reminder that when the underlying rate of a disease differs, the policy that makes sense differs too.

The Same Disease, a Different Moment

To see why screening works, it helps to remove the country from the picture and hold only one thing variable: when the cancer is found. The clearest way to do that is to look at survival by stage within the United States itself.

It is the same disease in each row. The only thing that changes is when it was found. And survival runs from about 99% down to about 29% for breast cancer, and from about 89% down to about 16% for colorectal cancer.

About 64% of breast cancers in the United States are caught at the localized stage. Screening is what produces that early share. The value of a mammogram or a colonoscopy is not a new treatment. It is an earlier moment.

The same logic explains the country gap. One study comparing national databases found five-year stomach cancer survival of 81% in Japan against 45% in the United States, and concluded that the wide difference could be largely explained by the stage at which the cancer was diagnosed. So the cancer survival rate by country is, in the end, a record of timing: who gets caught early, and who gets caught late.

So Why Does the United States Catch It Later?

If early detection works this well, the natural question is why American screening falls short of its own targets. The United States is not short on technology or testing facilities. The problem is that access to screening is uneven.

The numbers show it. In 2023, by the CDC‘s count, between one in three adults (colorectal) and one in five adults (breast) were not up to date on recommended screening, below the national targets. For colorectal cancer, only about 60% of adults aged 45 to 75 were current, even though the tests are widely covered by insurance. A major reason is that people who get an abnormal result on an initial test do not always complete the follow-up colonoscopy, held back by cost, scheduling, transportation, or simply not knowing what to do next.

Insurance status sorts who gets screened. Adults who are uninsured or underinsured have lower rates of breast, cervical, and colorectal screening than adequately insured adults. The money tells the same story. Of the roughly $43 billion the United States spent on initial cancer screening in 2021, about 88% was paid through private insurance, and privately insured people were screened at more than 1.66 times the rate of those on managed Medicaid. Who holds which insurance shapes who is found early.

Korea offers the contrast. Its national program lays the same screening system over everyone aged 40 and up, free or at a small share of the cost. The United States runs plenty of tests, but access bends with insurance, income, and geography. This is not a claim that American medicine is bad. It is that whether testing exists is a different question from whether everyone can reach it at the same moment. As the table in Part 1 turned out to be a matter of environment, screening turns out to be a matter of system design more than personal vigilance. Recent federal rules have started to lower some of these barriers, requiring no-cost follow-up after an abnormal colorectal test from 2023 and after an abnormal screening mammogram from 2026.

What Korea Did: From 7.4% to 63.8%

Korea’s National Cancer Screening Program began in 1999. Participation in stomach cancer screening rose from 7.4% in 2002 to 63.8% in 2022, driven by a well-organized endoscopy component, according to a national performance review. Adults aged 40 and older are offered an endoscopy every two years, with most of the cost carried by the state.

Over that same stretch, stomach cancer survival rose alongside the screening rate, a two-decade record of the two moving together. And the link is more than parallel lines. In a national study, people who took part in screening had 21% lower stomach cancer mortality than those who never did, and those screened by endoscopy had 47% lower mortality. Japan has run population screening for stomach cancer since the 1960s and added a Helicobacter pylori eradication program in 2013.

The United States, by contrast, has no national stomach cancer screening, because the disease is uncommon there. But it screens actively for breast and colorectal cancer. So the real difference between these countries is not whether they screen. It is which diseases they choose to screen for, and how evenly they reach their people.

The Limits of Screening

Screening does not solve everything, and an honest account says so. It carries real risks of its own: overdiagnosis, where a cancer that would never have caused harm is found and treated, along with false positives and unnecessary procedures. That is why countries weigh carefully which cancers to screen for, balancing incidence, cost, and the risk of overdiagnosis.

A good screening policy is not “test for everything.” It is a judgment about what is worth catching. That judgment is part of why the same disease is screened in one country and left alone in another.

Putting the Three Pieces Together

The table, in Part 1, makes a disease less likely to start. The body, in Part 2, helps it withstand more. Screening, in Part 3, catches what does start at an earlier point. The three pieces act on life expectancy at different points along the way.

Part 1 looked at the daily table and ultra-processed food, and Part 2 at how much the body moves. Set beside the 3.7-year gap this series opened with, none of these pieces is the whole answer. The gap is what it looked like from the start: many factors layered on top of one another. The cancer survival rate by country is one of those layers, not the entire story.

There is one piece this series has not yet touched. Finding a disease early is one thing. Paying for the treatment that follows is another. In most wealthy countries, the care after a diagnosis is largely covered by public insurance. In the United States, it is not. That cost is the subject of the next part, The Bill.

Plain-Language Reference

If you want to ask “where am I” after reading this part, a couple of the tools on this site line up with what it covered.

· Blood Work Decoder (read the numbers on a lab or screening report in plain language, the direct subject of this article)
· Testosterone Checker (one of the routine markers men 40 to 60 tend to track)

The Bottom Line

The cancer survival rate by country makes the point plainly. For the same stomach cancer, five-year survival is 39.8% in the United States, about 77% in Korea, and over 70% in Japan. A large part of that difference is when the cancer is found.

The same holds within a single country. Breast cancer caught early survives at about 99%, and at about 29% once it has spread. Colorectal cancer runs from about 89% to about 16% the same way. The moment of detection sorts the outcome.

The United States is not short on testing technology. Its screening is uneven, bent by insurance, income, and follow-up barriers, so one in three adults is not current on colorectal screening. Korea, over twenty years, raised stomach cancer screening from 7.4% to 63.8%, and survival rose with it.

This data does not tell anyone what to do. It only shows that the moment a disease is found can decide how the story ends. What to do with that is yours to decide.

This article is for general educational purposes and does not constitute medical advice. Survival figures come from national registries collected in different years and grouped in different ways, so they should be read as broad comparisons rather than exact rankings. Talk with your own physician about which screenings are right for you and when.

Take care of yourself. Nobody else will do it for you.